Infective endocarditis is most commonly caused by which organisms?

Infective endocarditis is most commonly caused by which organisms?

• A. Strep viridans, Staph aureus, and Enterococcus
• B. Strep pneumoniae
• C. Staphylococcus epidermidis
• D. Pseudomonas aeruginosa

Answer: (A)

Infective endocarditis is most often caused by bacteria that normally colonize the mouth, skin, and gastrointestinal tract. Streptococcus viridans is classically linked to subacute endocarditis after dental work, because these oral bacteria can enter the bloodstream during brushing or procedures and seed damaged valves. Staphylococcus aureus is now the leading cause of acute endocarditis, especially on abnormal native valves or prosthetic valves, and it tends to cause rapid, aggressive infection. Enterococcus species, from the GI and GU tracts, are a common cause in older adults and after urinary or intestinal procedures. Together, these three groups account for the majority of endocarditis cases in many clinical settings. Streptococcus pneumoniae is less commonly a cause of endocarditis overall. Staphylococcus epidermidis is particularly associated with prosthetic valve or intravascular-device-related endocarditis but is not the most common cause across all presentations. Pseudomonas aeruginosa is less common except in specific situations like intravenous drug use or nosocomial infections.

Infective endocarditis is most often caused by bacteria that normally colonize the mouth, skin, and gastrointestinal tract. Streptococcus viridans is classically linked to subacute endocarditis after dental work, because these oral bacteria can enter the bloodstream during brushing or procedures and seed damaged valves. Staphylococcus aureus is now the leading cause of acute endocarditis, especially on abnormal native valves or prosthetic valves, and it tends to cause rapid, aggressive infection. Enterococcus species, from the GI and GU tracts, are a common cause in older adults and after urinary or intestinal procedures. Together, these three groups account for the majority of endocarditis cases in many clinical settings.

Streptococcus pneumoniae is less commonly a cause of endocarditis overall. Staphylococcus epidermidis is particularly associated with prosthetic valve or intravascular-device-related endocarditis but is not the most common cause across all presentations. Pseudomonas aeruginosa is less common except in specific situations like intravenous drug use or nosocomial infections.